The present invention relates to a method and a structure of an electro-optics device. More particularly, the present invention relates to a structure for packaging an electro-optics device with high efficiency and the forming method thereof.
There are many kinds of light-emitting diodes that are utilized now. According to the packaging method, the light-emitting diodes are classified as through-hold light-emitting diodes, surface-mounted light-emitting diodes, and flip-chip light-emitting diodes.
Referring to FIG. 1, a conventional packaging structure comprising a light-emitting cell fixed on a die carrier is shown. The light-emitting cell comprises an epitaxial structure 10 formed on a conventional substrate 20. The epitaxial structure 10 comprises an n-type semiconductor layer, an active layer, and a p-type semiconductor layer. With the progress that the semiconductor process has been making, after the epitaxial structure 10 is completed, a transparent substrate can be utilized to replace the conventional substrate 20 for increasing the light-emitting diode""s output intensity. In this way, the light emitted by the light-emitting diode is not absorbed by the opaque conventional substrate. The light-emitting cell can emit light from its top and bottom surfaces, thereby increasing its light-emitting efficiency.
As shown in FIG. 1, a die carrier 30, such as a lead frame, a print circuit board, or a header, is connected to the substrate 20 to form a first electrode of the light-emitting cell. The silver paste, conductive paste, or bond of eutectic is utilized to fix the cell-fixing surface 40 between the light-emitting cell and the die carrier 30. Then, a second electrode 50 of the light-emitting cell is connected to another end of the lead frame 35. Thereafter, when the power is supplied to the die carrier 30 and the lead frame 35, the epitaxial structure 10 of light-emitting cell can emit light.
Referring to FIG. 2, when the light-emitting cell""s substrate 70 is made of the electrically insulating material, the silver paste is utilized to fix the light-emitting cell on the cell-fixing surface 95 of the die carrier 100 as described above. Then, the first electrode 80 and the second electrode 90 on the light-emitting cell are respectively connected to the die carrier 100 and the lead frame 105. Thereafter, when the power is supplied to the die carrier 100 and the lead frame 105, the light-emitting cell""s epitaxial structure 60 can emit light.
However, because the conventional light-emitting cell is directly fixed on the die carrier, the light generated by the epitaxial structure is absorbed by the cell-fixing surface between the cell and the die carrier. Although the conventional substrate has been replaced by the transparent substrate, most of the light emitted from the substrate is still absorbed by the cell-fixing surface. Therefore, the light-emitting efficiency is decreased, so that the advantage of light emitted from both sides of the light-emitting cell cannot be fully presented.
According to the above background of the invention, the cell-fixing surface absorbs the light emitted from the LED cell, resulting in a disadvantage that the light-emitting efficiency is reduced after the LED cell is fixed on the die carrier. Hence, this invention provides a method and structure for packing a high efficiency electro-optics device.
It is therefore an objective of this invention to provide a method and a structure for packaging an electro-optics device. A transparent material is added between the die carrier and the electro-optics device, so that the light emitting from the electro-optics device is not directly absorbed by the cell-fixing surface.
It is therefore another objective of this invention to provide a method and a structure for packaging an electro-optics device. A light reflective layer is formed on the die carrier, and a pattern of the light reflective layer is designed to prevent the light from being reflected again back to the active layer, wherein the light reflection decreasing light-emitting efficiency.
It is therefore another objective of this invention to provide a method and a structure for packaging an electro-optics device. With the utilization of the present invention, the requirement of increasing the output power for the electro-optics device can be substantially achieved by increasing the optical path of the electro-optics device.
In accordance with all aspects of this invention, the invention provides a structure for a high efficiency electro-optics device, comprising: a die carrier; a light reflective layer located upon the die carrier for changing the emitted light to a reflected light and also making part of the emitted light unparallel to the direction of the reflected light; a transparent layer located on the light reflective layer; and an electro-optics cell fixing on the transparent layer, wherein a first electrode and a second electrode are electrically connected respectively to the die carrier and a lead frame.
In accordance with the aforementioned objects of this invention, this invention provides a method for forming a high efficiency electro-optics device, comprising: providing a die carrier; forming a light reflective layer upon a surface of the die carrier, wherein the light reflective layer has a pattern for changing an emitting light to a reflecting light and making part of the emitted light unparallel to the direction of the reflected light; forming a transparent layer upon the light reflective layer; fixing an electro-optics cell on the transparent layer; and respectively electrically connecting a first electrode and a second electrode of the electro-optics cell to the die carrier and a lead frame.